Digital x-ray detector and method for repairing a bad pixel thereof

ABSTRACT

Provided herein is a digital x-ray detector and a method for repairing a bad pixel thereof, the detector including a substrate; a gate line and a data line formed on the substrate such that the gate line and the data line intersect each other to form a pixel domain; a thin film transistor formed within the pixel domain such that the thin film transistor is adjacent to a portion where the gate line and the data line intersect each other, the thin film transistor including a gate electrode, an active layer, a source electrode and a drain electrode; a PIN diode which is formed within the pixel domain and which includes a lower electrode connected to the source electrode of the thin film transistor, a PIN layer formed on the lower electrode, and an upper electrode formed on the PIN layer; a bias line connected to the upper electrode of the PIN diode; and a scintillator arranged above the PIN diode, wherein on at least one of a surface of the drain electrode which faces the PIN diode and a surface of the PIN diode which faces the drain electrode, a groove is formed such that it expands a distance between the drain electrode and the PIN diode.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.14/700,752, filed Apr. 30, 2015; which claims the benefit under 35U.S.C. §119 of Korean Patent Application No. 10-2015-0014359, filed Jan.29, 2015, which are hereby incorporated by reference in their entirety.

BACKGROUND

Field of Invention

The following description relates to a digital x-ray detector wherein aPIN diode may be prevented from being damaged in a process of repairinga bad pixel using laser, and a method for repairing the bad pixelthereof.

Description of Related Art

Methods for detecting an x-ray include a method of directly detecting anx-ray and a method of indirectly detecting an x-ray by converting thex-ray into a visible ray and then detecting the x-ray using the visibleray.

An x-ray detector using the aforementioned indirect method consists ofan element to convert an x-ray into a visible ray, an element to convertthe visible ray into an electronic signal, and an element to convert theelectronic signal into an image signal. In other words, the x-raydetector using the indirect method is an apparatus configured to convertan emitted x-ray eventually into an image signal.

Hereinafter, a conventional indirect type digital x-ray detector(hereinafter referred to as a ‘digital x-ray detector’) will beexplained with reference to the drawings attached.

FIG. 1 is a schematic cross-sectional view illustrating a conventionaldigital x-ray detector; FIG. 2 is a schematic top view of theconventional digital x-ray detector; and FIG. 3 is an enlarged view ofmajor parts of FIG. 2.

As illustrated in FIGS. 1 to 3, the conventional digital x-ray detectorincludes a substrate 10, a gate line 20 and a data line 30 disposed onthe substrate 10 such that the gale line and the data line intersecteach other, a thin film transistor 40 formed on an intersecting regionof the gate line 20 and the data line 30, a PIN diode 50 disposed on apixel domain, a bias line 60 disposed above the PIN diode 50 such thatit is parallel to the data line 30, and a scintillator 70.

The thin film transistor 40 is formed on the substrate 40, and includesa gate electrode 21, an active layer 41, a source electrode 42 and adrain electrode 43.

The PIN diode 50 includes a lower electrode 51 that is electricallyconnected to the thin film transistor 20; a layer 52 that includes a P(Positive) type semiconductor layer, an I (Intrinsic) type semiconductorlayer, and an N (Negative) type semiconductor layer successivelydeposited on the lower electrode 51; and an ITO upper electrode 53.

The scintillator 70 is formed on the PIN diode 50 and serves to convertan x-ray into a visible ray.

Hereinafter, operations of such a conventional digital x-ray detectorwill be explained.

When an x-ray is emitted to the scintillator 70, the x-ray is convertedinto a visible ray in the scintillator 70, and then the visible ray istransmitted to the PIN diode 50. The visible ray transmitted to the PINdiode 50 is converted into an electronic signal in the PIN diode 50, andthe converted electronic signal is converted into an image signalthrough the thin film transistor, and is then displayed.

Generally, in a digital x-ray detector, from a minimum of tens ofthousands up to a maximum of tens of millions of pixels are formed withdifferent sizes and resolutions, and thus it would take too much failurecost to manufacture an array substrate such that all those tens ofthousands or tens of millions of pixels operate normally. Therefore,array substrates of fair quality if not the best quality are beingmanufactured as long as they satisfy minimum requirements.

However, due to the recent increasing demand from customers to improvethe display quality, efforts are being made for processes that couldrepair bad pixels.

Specifically, after an x-ray is converted into a visible ray in ascintillator, the visible ray is converted into an electronic signal ina PIN diode, and then the converted electronic signal is displayed as animage signal after going through a thin film transistor. Herein, shouldthere be a bad pixel that retains its state of being bright spot, thebright spot will be clearly recognizable. Accordingly, efforts are beingmade to provide a repair process that could keep the bad pixel in astate of a dark spot.

It is generally easy for a human eye to recognize a white spot on ablack background than a black spot on a white background, and thus toreduce the recognizability of a bad pixel, it is general to darkening orblackening the bad pixel.

Therefore, when manufacturing an array substrate for a digital x-raydetector, a bright bad pixel is repaired to appear darker while leavinga dark bad pixel as it is, thereby reducing the recognizability of thebad pixels.

In an array substrate for a conventional digital x-ray detector,darkening a bad pixel is performed by cutting a drain electrode 43 (“A”part shown in dotted lines in FIG. 3) of the thin film transistor 40 byemitting a laser.

However, in the pattern design of an array substrate of such aconventional digital x-ray detector, the distance between the drainelectrode 43 and a PIN diode is too close to perform the repair process,and thus the PIN diode 50 may be damaged by the laser in the process ofcutting the drain electrode 43 using the laser, and when the PIN diode50 is damaged, the unstable state of a current may affect a PIN diode ofa neighboring pixel as well, causing the PIN diode 50 of the neighboringpixel to malfunction. Thus, performing the process of repairing a badpixel is not easy.

SUMMARY

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

A purpose of the present disclosure is to resolve the aforementionedproblems of prior art, that is to provide a digital x-ray detector withan increased distance between a drain electrode and a PIN diode so thatthe PIN diode may be prevented from being damaged during a process ofrepairing a bad pixel wherein laser is used, and a method for repairingthe bad pixel thereof.

According to an aspect, there is provided a digital x-ray detectorcomprising: a substrate; a gate line and a data line formed on thesubstrate such that the gate line and the data line intersect each otherto form a pixel domain; a thin film transistor formed within the pixeldomain such that the thin film transistor is adjacent to a portion wherethe gate line and the data line intersect each other, the thin filmtransistor including a gate electrode, an active layer, a sourceelectrode and a drain electrode; a PIN diode which is formed within thepixel domain and which includes a lower electrode connected to thesource electrode of the thin film transistor, a PIN layer formed on thelower electrode, and an upper electrode formed on the PIN layer; a biasline connected to the upper electrode of the PIN diode; and ascintillator arranged above the PIN diode, wherein on at least one of asurface of the drain electrode which faces the PIN diode and a surfaceof the PIN diode which faces the drain electrode, a groove is formedsuch that it expands a distance between the drain electrode and the PINdiode.

Herein, the groove may be formed on an area between the data line andthe active layer of the thin film transistor.

Furthermore, the groove may include a first groove formed on the drainelectrode side, and a second groove formed on the PIN diode side, thefirst groove and the second groove facing each other.

According to another aspect, there is provided a method for repairing abad pixel of a digital x-ray detector comprising a substrate; a gateline and a data line formed on the substrate such that the gate line andthe data line intersect each other to form a pixel domain; a thin filmtransistor formed within the pixel domain such that the thin filmtransistor is adjacent to a portion where the gate line and the dataline intersect each other, the thin film transistor including a gateelectrode, an active layer, a source electrode and a drain electrode; aPIN diode which is formed within the pixel domain and which includes alower electrode connected to the source electrode of the thin filmtransistor, a PIN layer formed on the lower electrode, and an upperelectrode formed on the PIN layer; a bias line connected to the upperelectrode of the PIN diode; and a scintillator arranged above the PINdiode, wherein on at least one of a surface of the drain electrode whichfaces the PIN diode and a surface of the PIN diode which faces the drainelectrode, a groove is formed such that it expands a distance betweenthe drain electrode and the diode, the method comprising the followingsteps: detecting the bad pixel by inspecting the digital x-ray detector;and darkening the detected bad pixel by cutting the drain electrodeusing laser at the position of the drain electrode corresponding to thegroove.

Various aforementioned aspects of the present disclosure have an effectof providing a digital x-ray detector with an increased distance betweena drain electrode and a PIN diode so that the PIN diode may be preventedfrom being damaged during a process of repairing a bad pixel whereinlaser is used, and a method for repairing the bad pixel thereof.

Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view illustrating a conventionaldigital x-ray detector.

FIG. 2 is a schematic top view of the conventional digital x-raydetector.

FIG. 3 is an enlarged view of the main parts of FIG. 2;

FIG. 4 is a schematic top view of the digital x-ray detector accordingto the present disclosure.

FIG. 5 is an enlarged view of the main parts of FIG. 4.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader ingaining a comprehensive understanding of the methods, apparatuses,and/or systems described herein. However, various changes,modifications, and equivalents of the systems, apparatuses, and/ormethods described herein will be apparent to one of ordinary skill inthe art. The progression of processing steps and/or operations describedis an example; however, the sequence of and/or operations is not limitedto that set forth herein and may be changed as is known in the art, withthe exception of steps and/or operations necessarily occurring in acertain order. Also, descriptions of functions and constructions thatare well known to one of ordinary skill in the art may be omitted forincreased clarity and conciseness.

The features described herein may be embodied in different forms, andare not to be construed as being limited to the examples describedherein. Rather, the examples described herein have been provided so thatthis disclosure will be thorough and complete, and will convey the fullscope of the disclosure to one of ordinary skill in the art.

Hereinafter, a digital x-ray detector according to a first embodiment ofthe present disclosure will be explained in detail with reference to thedrawings attached.

FIG. 4 is a schematic top view of a digital x-ray detector of thepresent disclosure; and FIG. 5 is an enlarged view of the main parts ofFIG. 4.

The digital x-ray detector according to the first embodiment of thepresent disclosure illustrated in FIGS. 4 and 5 includes a substrate110, a gate line 120, a data line 130, a thin film transistor 140, a PINdiode 150, a bias line 160 and a scintillator (not illustrated).

The gate line 120 is arranged on the substrate HO in a first direction,for example, an X axis direction of the figure, and the data line 130 isarranged on the substrate 110 in a second direction that isperpendicular to the first direction, for example, a Y axis direction.That is, the gate line 120 and the data line 130 are arranged such thatthey intersect each other and form a pixel domain.

The thin film transistor 140 is arranged within the pixel domain suchthat it is adjacent to where the gate line 120 and the data line 130intersect each other, and the thin film transistor 140 includes a gateelectrode 121 protruding from one side of the gate line 120, an activelayer 141 formed above the gate electrode 121, a drain electrode 143protruding from one side of the data line 130 and super posed on oneside of the active layer 141, and a source electrode 142 superposed onthe other side of the active layer 141.

Herein, the gate electrode 121 extends from the gate line 120.Therefore, the gate electrode 121 may be made of a same substance and inthe same process as the gate line 120.

The active layer 141 is formed on the gate electrode 121 and below thesource electrode 142 and drain electrode 143, and may include an ohmiccontact layer doped with an impurity formed on a region where itcontacts the source electrode 142 and drain electrode 143. That is, theactive layer 141 is formed on a middle layer between the gate electrode121, and the source electrode 142 and drain electrode 143, so as toserve as a channel through which electrons move.

The source electrode 142 is formed on one side of the active layer andis electrically connected to the PIN diode. Therefore, an electronicsignal converted at the PIN diode 150 is transmitted to the active layerthrough the source electrode 142 of the thin film transistor 140.

The drain electrode 143 is formed on the other side of the active layerthat faces the source electrode 142. The drain electrode 143 may beelectrically connected to the data line 130 through a predeterminedcontact hole. Therefore, the electronic signal goes through the drainelectrode 143 of the thin film transistor 140 and through the data line130 connected to the drain electrode 143, and is then displayed as animage signal.

The PIN diode 150 is electrically connected to the source electrode 142of the thin film transistor 140. The PIN diode 150 converts the visibleray into an electronic signal and transmits the converted electronicsignal to the source electrode 142.

The PIN diode 150 includes a lower electrode 151 electrically connectedto the source electrode 142, a PIN layer 152 formed on the lowerelectrode 151, and an upper electrode 153 formed on the PIN layer 152.The PIN layer 152 serves to convert the visible ray into the electronicsignal. Specifically, the PIN layer 152 includes a P (Positive) typesemiconductor layer, an I (Intrinsic) type semiconductor layer, and an N(Negative) type semiconductor layer, and the N type semiconductor layer,the I type semiconductor layer, and the P type semiconductor layer maybe deposited successively on the lower electrode 151. When a visible rayis emitted to such a PIN layer 152, the I type semiconductor layer isdepleted by the P type semiconductor layer and the N type semiconductorlayer, and generates an electric field inside thereof. A positive holeand electron generated by the ray are drifted by the electric field, andthen collected in the P type semiconductor layer and N typesemiconductor layer, respectively.

The bias line 160 may be electrically connected to the upper electrode153 of the PIN diode 150 through a predetermined contact hole 161.

The scintillator (not illustrated) is formed above the PIN diode 150,and serves to convert an x-ray into a visible ray.

According to the embodiment of the present disclosure, on a surface ofthe drain electrode 143 facing the PIN diode 150, a first groove 144 isformed that partially reduces a width of the drain electrode 143 in thefirst direction (X axis). Herein, the first groove 144 is desirablyformed where the drain electrode 143 is cut off in a repairing processusing laser aimed at making a bad pixel darker, that is between the dataline 130 and the active layer 141.

Furthermore, on a surface of the PIN diode facing the drain electrode143, a second groove 154 is formed to distance the PIN diode 150 awayfrom the drain electrode 143. Herein, the second groove 154 faces thefirst groove 144.

The first groove 144 and the second groove 154 expands the distancebetween the drain electrode 143 and the PIN diode 150, therebydistancing the drain electrode 143 away from the PIN diode 150.Accordingly, it is possible to prevent the PIN diode from being damagedin a process of cutting the drain electrode using laser when repairing abad pixel.

A width of the first groove 144 and the second groove 154 in the firstdirection (X axis) and a depth of the first groove 144 and the secondgroove 154 in the second direction (Y axis) are desirably set up suchthat they minimize a photo-electronic signal conversion efficiency ofthe PIN diode 150 and electrical characteristics of the drain electrode143 within a range that the Pin diode 150 is not damaged during therepairing process using laser.

A method for repairing a bad pixel by making the bad pixel darker in theaforementioned digital x-ray detector is explained hereinafter.

The method for repairing a bad pixel by making the bad pixel darkeraccording to the embodiment of the present disclosure includes a step ofdetecting the bad pixel, and a step of making the bad pixel darker.

The detecting the bad pixel may involve evenly emitting an x-ray on anentirety of surface of the digital x-ray detector, and detecting the badpixel by determining whether or not there is the bad pixel using animage signal being output from the digital x-ray detector.

The making the bad pixel darker may involve cutting the drain electrode143 of the bad pixel detected in the detecting of the bad pixel usinglaser, and making the bad pixel darker. Herein, the cut portion of thedrain electrode 143 using laser may be the portion where the firstgroove 144 is formed (“B” part shown in dotted lines in FIG. 5).

In such a method for repairing a bad pixel of the digital x-ray detectorof the present disclosure, during the process of cutting the drainelectrode 143 using laser, the laser is distanced away from the PINdiode 150 as much as the depth of the first groove 144 in the seconddirection (Y axis). Therefore, it is possible to prevent the PIN diode150 from being damaged in the repairing process, thereby increasing theyield rate of the panel.

Furthermore, since on the surface of the PIN diode 150 facing the drainelectrode 143, the second groove 154 is formed such that it correspondsto the first groove 144, the PIN diode 150 is further distanced from thedrain electrode 143 that is subjected to the cutting by the laser, by asmuch as the depth of the second groove 154 in the second direction (Yaxis). Therefore, it is possible to significantly reduce the possibilitythat the PIN diode 150 is damaged by the laser in the process ofrepairing the bad pixel by cutting the drain electrode 143 with laser.

While this disclosure includes specific examples, it will be apparent toone of ordinary skill in the art that various changes in form anddetails may be made in these examples without departing from the spiritand scope of the claims and their equivalents. The examples describedherein are to be considered in a descriptive sense only, and not forpurposes of limitation. Descriptions of features or aspects in eachexample are to be considered as being applicable to similar features oraspects in other examples. Suitable results may be achieved if thedescribed techniques are performed in a different order, and/or ifcomponents in a described system, architecture, device, or circuit arecombined in a different manner and/or replaced or supplemented by othercomponents or their equivalents. Therefore, the scope of the disclosureis defined not by the detailed description, but by the claims and theirequivalents, and all variations within the scope of the claims and theirequivalents are to be construed as being included in the disclosure.

REFERENCE NUMERALS

-   110: SUBSTRATE-   120: GATE LINE-   121: GATE ELECTRODE-   130: DATA LINE-   140: THIN FILM TRANSISTOR-   141: SOURCE ELECTRODE-   142: ACTIVE LAYER-   143: DRAIN ELECTRODE-   144: FIRST GROOVE-   150: PIN DIODE-   151: LOWER ELECTRODE-   152: PIN LAYER-   153: UPPER ELECTRODE-   154: SECOND GROOVE-   160: BIAS LINE-   161: CONTACT HOLE

What is claimed is:
 1. A method for manufacturing a digital x-ray detector comprising a substrate; a gate line and a data line formed on the substrate such that the gate line and the data line intersect each other to form a pixel domain; a thin film transistor formed within the pixel domain such that the thin film transistor is adjacent to a portion where the gate line and the data line intersect each other, the thin film transistor including a gate electrode, an active layer, a source electrode and a drain electrode; a diode which is formed within the pixel domain and which includes a lower electrode connected to the source electrode of the thin film transistor, a PIN layer formed on the lower electrode, and an upper electrode formed on the PIN layer; a bias line connected to the upper electrode of the PIN diode; and a scintillator arranged above the PIN diode, wherein the method comprises a step of forming a groove on at least one of a surface of the drain electrode which faces the PIN diode and a surface of the diode which faces the drain electrode, such that the groove increases a distance between the drain electrode and the PIN diode.
 2. The method according to claim 1, wherein the groove is formed on an area between the data line and the active layer of the thin film transistor.
 3. The method according to claim 2, wherein the groove includes a first groove formed on the drain electrode side, and a second groove formed on the PIN diode side, the first groove and the second groove are arranged to face each other.
 4. The method according to claim 1, further comprising the following steps: detecting the bad pixel by inspecting the digital x-ray detector; and darkening the detected bad pixel by cutting the drain electrode using laser at a location of the drain electrode corresponding to the groove.
 5. The method according to claim 2, further comprising the following steps: detecting the bad pixel by inspecting the digital x-ray detector; and darkening the detected bad pixel by cutting the drain electrode using laser at a location of the drain electrode corresponding to the groove.
 6. The method according to claim 3, further comprising the following steps: detecting the bad pixel by inspecting the digital x-ray detector; and darkening the detected bad pixel by cutting the drain electrode using laser a location of the drain electrode corresponding to the groove. 